Question about 0-marking

[jaw300t]

This is a question that perhaps Joan Bybee and Tom Givon could make clear to
me.  Tom Givon wrote:

>===== Original Message From Tom Givon <tgivon at OREGON.UOREGON.EDU> =====
>Dear JW--
>
>Now we are talking. But, I think, about a different topic.

Why is it a different topic now?  Tom mentions clause-chaining:

In clause-chains in
>discourse in an SVO language (like English), the first clause in the chain is
most
>typically fully marked with all the finite trimmings. Most of the
chain-medial
>clauses dispense with TAM marking, or use an invariant (less finite)
"narrative"
>marker that simply indicate "same as in the previous clause".

When I quoted from Joan Bybee's article in my first posting, was she excluding
zero-marked verbs in clause chains?  From her article "The Grammaticization of
Zero", the second sentence is, "When a grammaticizing overt morpheme becomes
obligatory, it may happen that other meanings within the same functional
domain, which previously had no grammatical expression, come to be expressed
by a meaningful zero."

In what kinds of environments do we find zero-marked verbs?  I understand that
some languages have ONLY zero-marked verbs (Indonesian?); I assumed that the
article referred to MORE than just those zero-marked verbs.  The article did
not specifically mention zero-marking in clause chains, but neither did it
specifically exclude them.

JWilson